Dietary soy protein and flax oil retard progression of advanced renal injury in adult Han:SPRD‐ cy rats

Abstract

Dietary soy protein and flax oil ameliorate the progression of early kidney disease in several experimental models, including the Han:SPRD-cy rat. However, individuals with kidney disease often do not become aware of their condition until injury to the kidney is extensive. The objective of this study was to determine whether initiating these interventions in established disease would alter further progression of renal injury. Two month old adult male Han:SPRD-cy rats were given either a flax oil diet (7% flax oil, rich in 18:3n-3), a soy protein diet (20% soy protein) or a control diet (7% corn oil, rich in 18:2n-6 and 20% casein) for 4 months. Renal fibrosis and cystic change were assessed morphometrically. Renal inflammation, cell proliferation (PCNA) and oxidant injury were measured immunohistochemically. Compared to controls, there was 21-25% less PCNA staining (P=0.0001), 21–24% less renal oxidant injury (P=0.0105) and 13–15% lower renal inflammation (P=0.0113) in flax oil and soy protein fed rats. Renal cystic growth, fibrosis and serum creatinine levels were not altered by these dietary treatments. Therefore, in addition to the potential reno-protective effects of flax oil and soy protein in slowing the progression of early renal disease, both dietary interventions also reduce renal injury in established kidney disease. (Supported by Natural Sciences and Engineering Research Council of Canada, Manitoba Institute of Child Health and the Manitoba Health Research Council)